Vapor-space inhibitors



United States Patent 3,398,095 VAPOR-SPACE INHIBITORS Clark W. Judd,Alton, Ill., assignor to Shell Oil Company, New York, N.Y., acorporation of Delaware No Drawing. Filed Nov. 13, 1967, Ser. No.682,571 16 Claims. (Cl. 25247.5)

ABSTRACT OF THE DISCLOSURE The corrosion prevention characteristics ofvolatile vapor-space inhibitors are greatly enhanced by the presence ofsulfurized oleic acid together with a member selected from (1) a C Cn-alkyl carboxylic acid and (2) a C -C n-alkyl carboxylic acid andcertain amines.

BACKGROUND OF THE INVENTION This invention relates to antirust lubricantcompositions and particularly to an antirust composition comprisingsulfurized carboxylic acid with conventional vapor-space inhibitors suchas fatty acids and alkyl or cyclic amines.

It is well known that the rusting of ferrous metal surfaces is a commonproblem in the field of lubrication. Accordingly, a large amount ofresearch effort has developed a great many additives which, when presentin lubricants in small amounts, inhibit corrosion of the surfaces withwhich the oil comes into contact. Reference to many of these inhibitorsis found in a book by Putilova et al., Metallic Corrosion Inhibitors,Pergamon Press, 1960. Although these known inhibitors are successful inreducing or eliminating corrosion of metal in contact wtih the liquid,they are generally ineffective for reducing corrosion in the vapor spaceabove the fluid. These preservative oils are adequate only "as long as acontinuous oil film of appreciable thickness is maintained. However,serious rusting problems have been encountered in certain infrequentlyoperated or stored equipment, especially when the humidity is high. Forinstance, a large amount of agricultural machinery is in operation onlyduring certain seasons of the year. F-rui-t picking and packingequipment may be idle for most of the year; for example, processingequipment in a winery may be in operation only a few weeks annually.Snow removal equipment must be in storage throughout the summer. Bothnew and used cars may remain for months in dealers lots with infrequentoperation. It is apparent that although known inhibitors would preventrusting of the metal surfaces in contact with the lubricating oil,corrosion could occur freely in the space above the oil level.

To prevent corrosion in the vapor space, it is generally necessary toinclude certain organic compounds known as vapor-space inhibitors.Effective vapor-space inhibitors are well known and, in general, includecertain fatty acids and amines, alone or in combination, with eachother. Effective as these vapor-space inhibitors may be, improvement isdesired.

SUMMARY It has now been discovered that oils containing sulfurizedcarboxylic acid in combination with known vapor-space inhibitors such asthe fatty acids and amines provide excellent corrosion inhibition forferrous metals not in contact with the fluid lubricant. The inhibitorcombination may be incorporated into formulations which are used assteam-turbine oils, hydraulic and circulating oils, factory-fill fuelsand lubricants, general preservative oils, greases, and the like. Thecombination is highly effective for preventing vapor-space corrosion insystems where water may be present in the oil.

I Patented Aug. 20, 1968 DESCRIPTION OF THE PREFERRED EMBODIMENTS Theinhibitor combination may be used in a variety of lubricants. Preferablythe lubricant is a mineral oil, such as that used in formulating turbineoil, circulating oil, hydraulic fluids, etc. Typical properties of asuitable mineral oil for use in the invention are:

GR, API, 60 C. 25.3 Pour point, F. 20 Flash, F. COC 460 Viscosity:

SUS at F. 533 SUS at 210 F. 65.5 Viscosity index 97 The fatty acidssuitable for use in the inhibitor combination are those used asconventional vapor-space inhibitor agents and are preferably C to Cn-alkylcarboxylic acids. Of these acids, caprylic, pelargonic and capricare particularly preferred.

Alkylcarboxylic acids, such as pelargonic acid, are very effectiveoil-soluble vapor-space inhibitors by themselves in neutral and acidicsystems. However, the effectiveness of such an inhibitor can be extendedto basic systems, as well as improved, by adding to the acid an amine.

Amines suitable for use in the present compositions are thoseconventionally used as vapor-space inhibitors and include primary, andsecondary tertiary alkyl and cycloalklyl amines and other cyclic amines.In general, the amines contain from 4 to 18 carbon atoms. Amines whichare preferred for use in the inhibitor combination of the presentinvention are hexylamine, cyclohexylamine, dicyclohexylamine,N,N-dimethyl 1,3 propane dia mine, morpholine, tri-n-butylamine,piperidine and N,N-dimethly piperazine.

Suitable sulfurized carboxylic acids include the sulfurized acidsderived from C to C unsaturated hydrocarbon carboxylic acids andpreferably sulfurized fatty acids. Preferred are sulfurized fatty acidshaving from 12. to 18 carbon atoms, and particularly sulfurized oleic,linoleic acid and the like. Mixtures of the above acids may also beused. The preferred sulfurized acids are those derived from oleic acidor a mixture of olefinic acids which is predominantly oleic acid, viz.commercial grades of oleic acid.

The preparation of sulfurized fatty acids is well known and can beachieved simply by reacting the unsaturated acid, e.g., oleic acid, withfree sulfur at temperatures of about C. to 300 C. The amount of sulfurin the sulfurized acid may vary from about 5 to 15% w. Sulfurized oleicacid available commercially from Carlisle Chemical Works.

The concentration of the amine, alkylcarboxylic acid and sulfurizedolefinic acid, based on the total formulation can vary over wide ranges.Oil formulations containing .concentrations ranging from 0.01 to 1.0%sulfurized carboxylic acid 0.05 to 0.5% alkylcarboxylic acid and 0.1 to0.5% amine, if present, are quite suitable. For example, 0.03% w.sulfurized oleic acid plus 0.1% w. pelargonic acid and 0.2% w.dicyclohexylamine, are

satisfactory to provide effective VSI properties in circulating oils.Doubling the concentrations ofthe respective compounds in circulatingoil formulations does not noticeably change the vapor space inhibitorproperties of the oil.

Other additives may also be added to the oil formulations of the presentinvention containing the inhibitor combination to improve itsperformance. These additives include, for example, antifoam agents,oxidation inhibitors, such as hindred phenols and aromatic amines,dispersants, pour point depressants, extreme pressure agents, liquidphase rust inhibitors, such as C2042 alkyl succinic acids, and viscosityimprovers.

Illustrative examples of formulations according to the inventioncomprise.

Composition A: Percent w. Sulfurized oleic acid 0.02 Dicyclohexylamine0.2 Pelargonic acid 0.1 C2042 alkyl succinic acid 0.03 Minerallubricating oil, balance.

Composition B:

Sulfurized linoleic acid 0.03 Dicyclohexylamine 0.15 Pelargonic acid0.13 C2042 alkyl succinic acid 0.01 Mineral lubricating oil, balance.

Composition C:

Sulfurized linoleic acid 0.02

Dicyclohexylamine 0.25 Caprylic acid 0.15 C2042 alkyl succinic acid 0.05Mineral lubricating oil, balance.

Composition D:

Sulfurized oleic acid 0.02

Dicyclohexylamine 0.20 Capric acid 0.10 C2042 alkyl succinic acid 0.1Mineral lubricating oil, balance.

Composition E:

Sulfurized oleic acid 0.02 Morpholine 0.20 Pelargonic acid 0.15 C2042alkyl succinic acid 0.03 Mineral lubricating oil, balance.

Composition F:

Sulfurized oleic acid 0.04 Piperidine 0.25 Pelargonic acid 0.12

Mineral lubricating oil, balance.

CompositionzG:

Sulfurized oleic acid 0.02 Hexylamine 0.20 Pelargonic acid 0.10

Mineral lubricating oil, balance.

Composition H:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 Pelargonic acid 0.10C2042 alkyl succinic acid 0.03 Phenyl-alpha-naphthylamine 0.102,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition J:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 Caprylic acid 0.10Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50Mineral lubricating oil, balance.

To illustrate the effectiveness of the inhibitor combination incompositions of the present invention with respect to vapor-spaceinhibitor (VSI) properties, a comparison is made with the followingcompositions:

Composition K: Percent w. Dicyclohexylamine 0.20 Pelargonic acid 0.10C2042 alkyl succinic acid 0.03 Phenyl-alpha-naphthylamine 0.102,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition L:

Sulfurized oleic acid 0.02 Phenyl-alpha-naphthylamine 0.102,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition M:

Sulfurized oleic acid 0.02 Phenyl-alpha-naphthylamine 0.102,6-di-t-butyl-4-methyl phenol 0.50 Pelargonic acid 0.05 Heptanoic acid0.05 Mineral lubricating oil, balance.

Composition N:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 C2042 alkyl succinicacid 0.03 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol0.50

Mineral lubricating oil, balance.

To test the eflectiveness of the vapor-space inhibitor agents in thevarious compositions, the compositions Were subjected to a F. corrosiontest. This test consists of suspending a freshly polished and cleanedmild steel block, 1.8 cm. x 1.8 cm. x 0.6 cm., in the upper portion of a250 ml. Erlenmeyer flask from a watch glass which covers the flask. 5ml. of the oil composition to be tested and 10 ml. distilled Water areplaced in the flask. The flask is immersed in an oil bath at 150 F. to adepth of 5 cm. The steel block was examined after 7 days; if there were6 specks or more of rust, the oil composition was considered to havefailed the test. Compositions H, J, K, L, M and N were tested. Theresults of these tests are given in Table 1.

TABLE 1 Composition Run No. Result 1 Pass 1 Do. 1 Fail 1 Do. 1 Pass 1Fail.

The results of Table 1 show that the compositions of the presentinvention possessed satisfactory vapor-space inhibitor properties(Compositions H and I), whereas compositions in which the sulfurizedoleic acid, amine and/or alkylcarboxylic acid was omitted, did not havesatisfactory vapor-space inhibitor properties.

I claim as my invention:

1. A lubricating oil composition comprising a major amount of alubricating oil and a minor amount, sufficient to impart vapor-spaceinhibiting properties, of a vaporspace inhibitor consisting of asulfurized C unsaturated carboxylic acid and a member selected from thegroup consisting of (1) a C n-alkylcarboxylic acid and (2) a C Cn-alkylcarboxylic acid and an amine selected from the group consistingof alkylamines cycloalkylamines, morpholine, piperidine and N,N-dimethyl piperazine.

2. The composition of claim 1 wherein the vapor space inhibitor consistsof 0.01 to 1.0% of a sulfurized C 5 unsaturated carboxylic acid, 0.05 to0.5% of a C n-alkylcarboxylic acid and 0.01 to 05.% of an amine selectedfrom the group consisting of alkylamines, cycloalkylamines, morpholine,piperidine and N,N-dimethyl piperazine.

3. The composition as defined in claim 2 wherein the olefinic acid isoleic acid.

4. The composition of claim 3 wherein the amine is morpholine.

5. The composition of claim 3 wherein the amine is dicyclohexylamine.

6. The composition of claim 5 wherein the n-alkylcarboxylic acid iscaprylic acid.

7. The composition of claim 5 wherein the n-alkylcarboxylic acid iscapric acid.

8. The composition of claim 5 wherein the n-alkylcarboxylic acid ispelargonic acid.

9. The composition of claim 8 wherein the composition contains from 0.01to 0.05% w. sulfurized oleic acid, from 0.1 to 0.5% W. dicyclohexylamineand from 0.05 to 0.5% W. pelargonic acid.

10. The composition of claim 8 wherein the composition contains 0.02%sulfurized oleic acid, 0.20% w. dicyclohexylamine and 0.10% w.pelargonic acid.

11. The composition of claim 1 wherein the vaporspace inhibitor consistsof 0.01 to 1.0% of a sulfurized C unsaturated carboxylic acid and 0.05to 5.0% of a C n-alkylcarboxylic acid.

12. The composition of claim 11 wherein the unsaturated carboxylic acidis oleic acid.

13. The composition of claim 12 wherein the n-alkylcarboxylic acid ispelargonic acid.

14. The composition of claim 12 wherein the n-alkylcarboxylic acid iscaprylic acid.

15. The composition of claim 12 wherein the n-alkylcarboxylic acid is amixture of pelargonic and heptanoic acids.

16. The composition of claim 12 wherein the n-alkylcarboxylic acid iscapric acid.

References Cited UNITED STATES PATENTS 2,257,752 10/1941 Lincoln et al.252-475 XR 2,268,608 1/ 1942 McNulty et al. 252-475 XR 2,368,605 1/1945White 252-486 XR 2,829,945 4/1958 Krieg 21-25 3,169,116 2/1965 Basemanet al. 21-2.7 XR

DANIEL E. WYMAN, Primary Examiner.

25 W. H. CANNON, Assistant Examiner.

